Math code?

Hi everyone,

I just purchased Robert Penner’s book and I was looking at part of his explanation of “static objects”. He implements his own Math function, the code is:
[AS]Math.cube = function (x){
return xxx;
trace(Math.cube(20));[/AS] According to Mr.Penner, the trace function will give 8000, however, when I entered this in the actions window the output is two error messages. I am using Flash MX 2004. I was wondering why this is happening, and if anyone could help me clear this up.

Thanks A Lot